// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_AUDIO_AUDIO_OUTPUT_PROXY_H_
#define MEDIA_AUDIO_AUDIO_OUTPUT_PROXY_H_

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/threading/non_thread_safe.h"
#include "media/audio/audio_io.h"
#include "media/base/audio_parameters.h"

namespace media {

class AudioOutputDispatcher;

// AudioOutputProxy is an audio otput stream that uses resources more
// efficiently than a regular audio output stream: it opens audio
// device only when sound is playing, i.e. between Start() and Stop()
// (there is still one physical stream per each audio output proxy in
// playing state).
//
// AudioOutputProxy uses AudioOutputDispatcher to open and close
// physical output streams.
class MEDIA_EXPORT AudioOutputProxy
    : public AudioOutputStream,
      public NON_EXPORTED_BASE(base::NonThreadSafe) {
public:
    // Caller keeps ownership of |dispatcher|.
    explicit AudioOutputProxy(base::WeakPtr<AudioOutputDispatcher> dispatcher);

    // AudioOutputStream interface.
    bool Open() override;
    void Start(AudioSourceCallback* callback) override;
    void Stop() override;
    void SetVolume(double volume) override;
    void GetVolume(double* volume) override;
    void Close() override;

    AudioOutputDispatcher* get_dispatcher_for_testing() const
    {
        return dispatcher_.get();
    }

private:
    enum State {
        kCreated,
        kOpened,
        kPlaying,
        kClosed,
        kOpenError,
        kStartError,
    };

    ~AudioOutputProxy() override;

    base::WeakPtr<AudioOutputDispatcher> dispatcher_;
    State state_;

    // Need to save volume here, so that we can restore it in case the stream
    // is stopped, and then started again.
    double volume_;

    DISALLOW_COPY_AND_ASSIGN(AudioOutputProxy);
};

} // namespace media

#endif // MEDIA_AUDIO_AUDIO_OUTPUT_PROXY_H_
